Various proposals have been put forward for passive safety belt systems, that is, occupant restraining belt systems which automatically move to an occupant-restraining configuration when an occupant enters the vehicle and move to an occupant-releasing position when the occupant leaves the vehicle. Some of the proposed systems use wire and pulley drives or racked wire drives powered by an electric motor or a mechanical motion amplifier to move belt guide rings from one position to another. Such systems require numerous components, complicated vehicle assembly procedures and, in general, considerably increase the cost of the vehicle. Such devices may be prone to service and reliability problems, depending on the particular design, in many cases.
A much simpler and less costly passive occupant restraint system that has recently come into use comprises an energy-absorbing knee bolster located under the dashboard and capable of minimizing injury to the lower body and legs of a vehicle occupant and a passive shoulder belt which leads from an inboard position below and behind the occupant to an upper rear corner of the door. In some cases, the belt retractor is located at the inboard location and the outboard end of the shoulder belt is secured to an anchor. In other cases, the inboard end of the belt is fixed and the retractor is located between the inner and outer door panels and leads up from the retractor through a belt guide ring affixed near the upper rear corner of the door.
FIG. 1 of the accompanying drawing shows a prior art passive shoulder belt. The belt 10 leads upwardly from an emergency locking retractor 12 installed in the door 14 through a belt guide 16 that is fastened to the door near the upper rear corner and leads inwardly and downwardly across the vehicle seat 18 to an inboard fastening point constituted by an emergency release buckle 20. One end of a control tape 22 is fastened to the belt 10 at a distance from the buckle 20 such that when the door is closed and the belt is in the occupant-restraining configuration, the fastening point where the tape 22 is attached to the belt is located near the guide ring 16. The other end of the tape 22 is fastened to a slider 24 that runs forward and backward along a guide bar 26. When the door is opened, it moves forwardly and outwardly relative to the inboard end of the belt. Therefore, an additional length of belt is pulled from the retractor 12. Meanwhile, the distance between the buckle 20 and the point where the control tape 22 is fastened to the belt 10 remains the same. The slider 24 moves along the guide bar 26 to a forward position, as shown in FIG. 1. Accordingly, the control tape holds an intermediate part of the belt in the occupant-releasing configuration upwardly and forwardly from the position it would otherwise assume, were the tape not included.
Although the system shown in FIG. 1 has, by reason of the control tape arrangement, the advantage of a better occupant-releasing configuration than a system not having the control tape arrangement (i.e., a passive shoulder belt which leads directly from the inboard location to the upper rear corner of the door), the belt still gets in the way of an occupant who is entering or leaving the vehicle because the tape allows the intermediate part of the belt to remain a substantial distance rearwardly from the front pillar.